Aqueous black enamel composition for glass substrate

ABSTRACT

The invention relates to a water-based black enamel composition capable of being deposited on a glass substrate, especially on a glass sheet, which comprises:  
     20 to 40% by weight of water-soluble sodium silicate and/or potassium silicate;  
     a water-soluble base, in an amount sufficient for the pH of the composition to be at least 10.5;  
     5 to 25% by weight of water;  
     40 to 60% by weight of a metal oxide chosen from the group consisting of copper oxides, iron oxides, cobalt oxides, mixtures of these oxides and mixtures of at least one of said oxides with chromium oxide(s);  
     less than 10% by weight of zinc oxide;  
     at least 10% by weight of a glass frit having a melting point below 680° C.; and  
     less than 10% by weight of a glass frit having a Littleton point above 700° C.  
     The invention also relates to glazing, especially automobile glazing, comprising at least one glass sheet, at least one of the faces of which is coated at least partially with the aforementioned enamel composition.

[0001] The invention relates to a water-based black enamel compositionwhich can be deposited on a glass substrate and to the resultingenameled substrates, particularly enameled glazing.

[0002] It is known to use enamel compositions on glass substrates,especially glazing for automobiles or buildings, in order to formdeposits of all kinds, for example decorative, conductive or protectivelayers or layers intended to form masks.

[0003] These enamel compositions serve especially to form the opaqueperipheral band, of dark color, generally solid but possibly alsoincluding apertures, which is found on windshields, side windows andrear windows of motor vehicles. The function of the band is twofold.Firstly, it allows the integrity of the adhesive lying under the glazingto be preserved, when the glazing is mounted in the body opening bybonding, forming a screen against solar radiation, more particularlyultraviolet radiation. Secondly, it improves the external appearance ofthe vehicle by masking the electrical or other connection elementslocated around the border of the internal face of the glazing, as isespecially the case for rear windows.

[0004] In general, the enamel compositions useful for forming such aband are formed from a powder comprising a glass frit (which has to formthe glassy matrix) and pigments (especially as gray or black colorants,these pigments possibly forming part of the frit) and from a medium. Thepigments are most often metal oxides, such as chromium, cobalt, nickeland iron oxides, which do not react with the other constituents of thecomposition. The medium ensures that the solid particles are in correctsuspension and allows application and temporary adhesion of the enamelto the substrate. In general, the medium contains organic solvents, suchas pine oil or terpenes, mineral oils, diluents and/or resins, orUV-crosslinkable components.

[0005] The enamel composition is generally deposited on the surface ofthe glass substrate by screen printing, spraying, curtain coating orroll coating, and then it is fixed to the glass. The fixing operation isnecessary in order to allow the substrate to be handled, for example forthe purpose of bending it and/or toughening it, without any risk ofdamaging the enamel layer. Depending on the medium used, the fixing mayconsist of a drying operation, for example carried out by simply heatingto a moderate temperature (of around 80-150° C.) so as to remove theorganic solvent(s), or of a UV curing operation when the medium iscrosslinkable.

[0006] One of the problems with the existing enamel compositions is thepresence of solvents, especially organic solvents. Because of thetoxicity of some of them with which users come into contact, and alsobecause of their possible environmental risks, attempts have been madeto replace them with water.

[0007] Water-based enamel compositions are known, which contain awater-soluble sodium silicate, a water-soluble base, a metal oxidepowder and a glass frit having a melting point below 1 300° F. (=704°C.) (U.S. Pat. No. 5,518,535) and also zinc oxide (U.S. Pat. No.5,698,026) or glass particles having a melting point above 1 700° F.(=926° C.) (U.S. Pat. No. 5,677,064).

[0008] However, the abovementioned water-based compositions havedrawbacks. With such compositions, it is difficult to obtain a coatinghaving a fusibility compatible with the temperature conditions appliedduring the forming of laminated glazing. This is because, at the appliedtemperature, which in general does not exceed 650° C. (the temperatureof the glass), the enamel has a tendency to exhibit a residual capillaryeffect because of insufficient sintering. Moreover, the enamel obtainedunder the bending conditions does not have the expected properties interms of color. On clear (untinted) glass, the enamel formed has asomewhat intense gray tint, this tint being furthermore chromaticallynon-neutral. Depending on the type of pigment(s) used, the absence ofchromatic neutrality results in a gray coloration tending toward red,green, blue or yellow. Finally, although it is possible on tinted glassto obtain a black enamel, this coloration does not have the desired“intensity” (or “depth”); in particular, it has an L* valuesubstantially greater than that defined later in the text.

[0009] The present invention provides a novel water-based enamelcomposition which allows the aforementioned drawbacks to be remedied.The composition according to the invention can be deposited on a glasssubstrate, exhibits excellent bonding to the glass after drying (andconsequently excellent scratch resistance), is antisticking at thebending temperatures and makes it possible to obtain, after baking, ablack enamel forming a uniform coating of good durability.

[0010] Another subject of the invention is an enamel composition thatcan be deposited on a clear glass substrate in order to form achromatically neutral black enamel, this composition furthermore havingthe advantages of the composition defined in the previous paragraph.

[0011] Another subject of the invention is glass substrates coated withthe aforementioned enamel compositions, especially enameled glazing,particularly laminated glazing for automobiles.

[0012] In the present invention, the term “enamel composition” isunderstood to mean the enamel composition in question before it has beenbaked, the enamel after baking being essentially in the form of acolored glassy matrix.

[0013] The term “black enamel” is understood according to the inventionto mean an enamel which, after baking, has an L* value of less than orequal to 8, preferably less than or equal to 6.

[0014] The expression “chromatically neutral black enamel” is understoodaccording to the invention to mean an enamel which, after baking, hasthe following colorimetric coordinates, in absolute values:

[0015] L*≦8; |a*|≦1 and |b*|≦1 and preferably L*≦6; |a*|≦0.6 and|b*|≦0.6.

[0016] The colorimetric coordinates L*, a* and b* were defined andproposed in 1931 by the CIE (Commission Internationale de I'Eclairage[International Illumination Commission]) and have formed the subject ofan official CIE recommendation in 1976 (International IlluminationCommission, Colorimetry—Official Recommendations—CIE Publication No.15-2, Vienna, 1986). The abovementioned colorimetric coordinates aremeasured in reflection, using a Minolta CM 2002 spectrocolorimeter,under illuminant D₆₅ and at an angle of observation of 10° and inspecular excluded mode.

[0017] The term “clear glass” is understood here to mean a glass whoselight transmission factor TL under illuminant D₆₅ is greater than orequal to 90%, measured on a glass sheet 4 mm in thickness with parallelfaces.

[0018] According to the invention, the water-based black enamelcomposition capable of being deposited on a glass substrate, especiallyon glazing, comprises:

[0019] 20 to 40% by weight of water-soluble sodium silicate and/orpotassium silicate;

[0020] a water-soluble base, in an amount sufficient for the pH of thecomposition to be at least 10.5;

[0021] 5 to 25% by weight of water;

[0022] 40 to 60% by weight of a metal oxide chosen from the groupconsisting of copper oxides, iron oxides, cobalt oxides, mixtures ofthese oxides and mixtures of at least one of said oxides with chromiumoxide(s);

[0023] less than 10% by weight of zinc oxide;

[0024] at least 10% by weight of a glass frit having a melting pointbelow 680° C.; and

[0025] less than 10% by weight of a glass frit having a Littleton pointabove 700° C.

[0026] In the present invention, the term “melting point” has themeaning commonly accepted in the enamel field, i.e. it denotes thetemperature at which a glass frit is sufficiently molten to bond to theglass on which it has been deposited and form an impermeable vitreouslayer. This “melting point” is also called the “baking temperature” or“fusing temperature”. It corresponds to the minimum temperature at whichthe frit exhibits “sufficient” sintering, this “sufficient” sinteringbeing manifested by the disappearance of the capillary effect. Inpractice, this consists for a person skilled in the art in determiningthe temperature at which a frit deposited on a glass substrate must bebaked in order to form a layer having a porosity such that a liquidcannot pass through it. Hereafter, the expression “glass frit having amelting point below 680° C.” will be called “low-melting-point frit”.

[0027] Also according to the invention, the term “Littleton point” or“(Littleton) softening point” has the meaning recognized in the glassfield. The “Littleton point” corresponds to the temperature of a glasshaving a viscosity of 10^(7.6) poise, measured under standardizedconditions (ASTM C 338). Hereafter, the expression “glass frit having aLittleton point above 700° C.” will be called “refractory frit”.

[0028] According to the invention, the water-soluble sodium silicateand/or potassium silicate represents from 20 to 40% by weight,preferably 20 to 30% by weight, of the enamel composition. The silicatemay comprise only one sodium silicate or potassium silicate, or amixture of several sodium silicates and/or potassium silicates.Preferably, the enamel composition does not contain potassium silicate.

[0029] Water represents from 5 to 25% by weight, preferably 10 to 20% byweight, of the composition.

[0030] The water-soluble base according to the present invention is usedin a sufficient amount for the pH of the composition to be at least10.5, preferably greater than 12.5 and even better greater than 13.5. Todo this, any type of known water-soluble base, for example sodiumhydroxide or potassium hydroxide, can be used. Sodium hydroxide ispreferred. The highly basic nature makes it possible in particular toensure that the composition is well preserved over time.

[0031] The metal oxide represents from 40 to 60% by weight, preferably50 to 60% by weight, of the composition according to the invention. Themetal oxide is chosen from the group consisting of copper oxides, ironoxides, cobalt oxides, mixtures of these oxides, and mixtures ofchromium oxide(s) and at least one of said oxides, which give the enamelthe desired black coloration. Preferably, the metal oxide is chosen frommixtures of chromium oxide(s) and copper and/or iron oxide(s).

[0032] In one advantageous embodiment, especially when the substrate tobe coated is made of clear glass, the metal oxide is copper chromite(Cr₂O₃.CuO), iron chromite (Cr₂O₃.FeO) or a mixture of these chromites(preferably containing more than 50% by weight of copper chromite).Particularly preferably, the metal oxide consists entirely of copperchromite.

[0033] The metal oxide is in general in a finely divided form, theaverage particle size being less than 7 μm, preferably between 5 and 7μm and advantageously less than 5 μm.

[0034] Zinc oxide represents less than 10% by weight, preferably 1 to 6%by weight and better still 4 to 6% by weight, of the compositionaccording to the invention. The zinc oxide acts as a promoter ofadhesion of the components of the composition to the glass. It has theeffect of improving the compatibility of the enamel with the glass,especially by reducing the difference between the expansion coefficientsof the enamel and the glass.

[0035] The low-melting-point frit represents at least 10%, preferably 10to 30% and better still 10 to 25%, by weight of the compositionaccording to the invention. As examples, mention may be made ofbismuth-borosilicate glass frits, zinc-borosilicate glass frits andlead-borosilicate glass frits (even though the latter are not desirable,essentially for reasons associated with the presence of lead in theenvironment). The glass frit according to the invention may consist of asingle frit or a mixture of several frits chosen from the aforementionedfrits. Advantageously, especially when the frit content exceeds 20%, itis a bismuth-borosilicate or zinc-borosilicate glass frit containingnucleating seeds capable of making the frit crystallizable. The use ofsuch a frit makes it possible in particular to improve the antistickproperties of the enamel when bending pairs of glass panes for thepurpose of forming laminated glazing, which makes it possible to avoidtransfer of the enamel on that face of the glass facing the coating.Bismuth-borosilicate glass frits are preferred, especially because theyoffer greater resistance to chemical agents. In a preferred embodiment,especially for the production of laminated glazing, the melting point ofthe glass frit is below 600° C. and is advantageously between 500 and600° C.

[0036] In the composition according to the invention, the refractoryfrit content is less than 10% by weight, preferably varies from 4 to 10%and better still is between 0 and 4%. In general and preferably,especially when it relates to laminated glazing, the composition doesnot contain a refractory frit. As examples, mention may be made ofsoda-lime glass frits, such as float glass. The refractory frit isgenerally in the form of particles whose average size is less than 20μm, preferably varying from 3 to 15 μm and better still from 5 to 7 μm.

[0037] Apart from the aforementioned essential constituents, thecomposition according to the invention may contain a small amount (ingeneral less than 1%, preferably less than 0.5%, by weight) of asurfactant acting as a wetting agent with respect to the glass.

[0038] The composition according to the invention may also containingredients for lowering the expansion coefficient, of the ceramic frittype with a low expansion coefficient, especially one based on zirconiumor alumina (zirconium silicate or alumina silicate in proportionsranging from 5 to 25% and preferably from 10 to 20%.

[0039] The amount added depends on the base composition of the enamel,on the composition of the glass, on the profile of the edge of theglass, on the position of the enamel with respect to the edge of theglass and on the thickness of the enamel.

[0040] In particular, the addition is greater if the enamel is depositedright to the edge of the glass and if this edge is fashioned so as to berounded, favoring therefore greater enamel thicknesses, of the order of100 microns or more at the extremity of the glass. This is because,owing to the high expansion coefficient of this type of enamel,extension stresses are then generated in the glass, stresses which maybe harmful.

[0041] Since the expansion-coefficient-lowering ingredients areinfusible, their particle size is preferably chosen to be small,preferably less than 20 microns, so as not to impair the appearance ofthe enamel, particularly its roughness.

[0042] The composition according to the invention may be prepared bysimple blending of the various constituents in an appropriate device,for example a ball mill, for a time long enough to obtain a homogeneousblend. The blending is generally carried out at room temperature (around25 to 30° C.). However, it is preferred to use the method consisting indissolving the sodium silicate, and where appropriate the potassiumsilicate, in water, preferably with vigorous stirring, and in adding theother constituents of the composition to said solution, the order ofintroduction not being critical.

[0043] The blend obtained is then deposited on a glass substrate. Theglass used may belong to any type of glass normally used in the glazingfield for automobiles or buildings, such as soda-lime glass (floatglass).

[0044] To deposit the blend on the glass, any method known in the fieldin question may be used, for example screen printing, spraying, curtaincoating or roll coating. When screen printing is used, this being thepreferred method, it is recommended to keep the suitable device undercontrolled humidity conditions, advantageously in a relative humidityclose to 80 to 85%, as described in U.S. Pat. No. 5,509,964.

[0045] The shape, size and number of the coatings on one or more facesof the glass substrate depend substantially on the use for which it isintended. In automobiles, at least one coating is generally appliedaround the perimeter of the glazing in the form of a band of variablewidth, but with a width, however, sufficient to mask the elementslocated beneath the glazing, these possibly being adhesives and/orconnection elements, especially electrical connection elements, asindicated above.

[0046] The thickness of the coating can vary according to the envisioneduse. In the case of the aforementioned band, the thickness varies ingeneral from 15 to 35 μm and preferably from 20 to 28 μm.

[0047] Once the composition according to the invention has been coatedonto it, the substrate is heated to a temperature high enough toeliminate the water and allow the coating to bond to the glass. Thistemperature is, however, below the softening temperature of thesubstrate, so as to prevent any deformation of the glass causing opticaldefects, the latter absolutely having to be avoided when producingautomobile glazing, such as windshields. In general, the heating iscarried out at a temperature below 500° C., and preferably 250° C. Forthis purpose, it is possible to use any known means, for examplemicrowave or infrared radiation. When several layers are deposited onthe substrate, each layer is preferably dried before the next layer isdeposited. Preferably, the substrate comprises only a single enamellayer according to the invention.

[0048] The glass sheet coated with the enamel composition on at leastone of its faces, preferably only a single face, is baked, the bakingtaking place, where appropriate, during the heat treatment associatedwith the bending and/or toughening of the substrate.

[0049] The glass substrate is bent using methods known per se at abaking temperature generally of around 560 to 640° C., preferably about580-600° C. (“slight” bending) and 600-620° C. (“deep” bending), thistemperature being reached after a time preferably not exceeding aboutten minutes. The bending may be carried out by gravity, as is especiallythe case with glass substrates bent in pairs for the manufacture oflaminated glazing, or by means of dies.

[0050] Toughening of the glass substrate, especially used for monolithicglazing, is carried out using methods known per se at a temperaturegenerally of around 640 to 680° C. for a time not exceeding a fewminutes. When the substrate is bent and toughened, the toughening may becarried out after the enameled substrate has been bent, possibly in thesame device.

[0051] In one particularly advantageous embodiment, the substrate coatedwith the composition according to the invention is a clear glass sheetof variable thickness (generally from 1.6 to 2.6 mm, preferably from 2.1to 2.6 mm) intended to form a laminated pane, especially for anautomobile windshield. In this case, the glass sheet bearing the enamelcoating is joined to at least one other glass sheet, and the sheets arebent. Preferably, the second glass sheet is not coated with enamel andthe glass has the same composition as that of the first sheet.Advantageously, the thickness of the second glass sheet lies within theafore-mentioned limits, and better still is equal to that of the firstsheet. It is particularly advantageous for the glass sheets duringbending to be placed so that the face bearing the enamel compositionconstitutes the 2 face (the internal face of the external sheet) of thelaminated glazing in its final position. The bent glass sheets areseparated (separation being easier if there is no trace of bonding) soas to insert therebetween at least one insert film of differentmaterial, for example an organic material such as polyvinyl butyral, andthen they are joined together using heat and pressure to form thelaminated glazing.

[0052] The composition according to the invention is particularlysuitable for coating an unenameled glass substrate or a glass substratealready coated with one or more enamel layers. This substrate mayconsist of one or more glass sheets and may be toughened so as toexhibit improved mechanical strength and thermal resistance properties.The substrate coated with the enamel according to the invention thuscomprises at least one glass sheet coated over at least a portion of oneof its faces with at least one layer of an enamel having the compositionaccording to the invention.

[0053] The examples which follow allow the invention to be illustrated,without however limiting it.

[0054] In the examples, the melting point of the low-melting-point fritis determined by the method consisting in depositing the glass frit(15-30 μm thickness) on a glass sheet (length: 150 mm; width: 60 mm) andin heating according to a suitable temperature ramp having an amplitudeof about 100° C. (in general, two temperature ramps suffice, one varyingfrom 500 to 600° C., the other from 600 to 700° C.). After cooling toroom temperature, a line is drawn with a felt pen on the vitrified layerobtained (from the region of the layer corresponding to the lowesttemperature to that of the highest temperature), and, by looking throughthe substrate, the point at which a bright line (corresponding to thepenetration of the solvent(s) into said layer) appears is determined.The temperature associated with the aforementioned point corresponds tothe melting point of the frit.

[0055] The Littleton point of the refractory frit is determined underthe conditions of the abovementioned ASTM C 338 standard.

EXAMPLE 1

[0056] A black enamel composition was prepared by blending, at roomtemperature and with stirring (at around 100 rpm), the following parts Aand B (in percentages by weight): Part A: sodium silicate 23 water 11sodium hydroxide in an amount sufficient to obtain a pH of 10.5; Part B:copper chromite 52 zinc oxide 1 bismuth-borosilicate glass frit 13(around 600° C. melting point)

[0057] The enamel composition thus prepared was deposited on a clearglass sheet (PLANILUX®; thickness: 2.6 mm) by screen printing in a wetmedium (coating thickness: 25 μm). The sheet coated with the compositionwas heated to 220° C. (time: 3 minutes). After cooling, a uniformscratch-resistant coating having an L* value of 18 was obtained.

[0058] The aforementioned glass sheet (large pane) was placed on ahorizontal bending frame, the face coated with the enamel compositionturned upward, and a second sheet 2.1 mm in thickness, of slightlysmaller size (small pane), made of glass of the same type as the firstbut devoid of any enamel composition. The assembly was heated to about610-620° C. (duration: 8-10 minutes) and then cooled to roomtemperature. The large pane was coated with a black enamel about 16 μmin thickness, having the following colorimetric coordinates: L*=5−6;a*≦0.5 and b*≦0.5 (these coordinates being measured at 20 points on theenamel layer).

EXAMPLE 2

[0059] A black enamel composition was prepared by blending, at roomtemperature and with stirring (at around 100 rpm), the following parts Aand B (in percentages by weight): Part A: sodium silicate 23 water 11sodium hydroxide in an amount sufficient to obtain a pH of 10.5; Part B:copper chromite 41 zinc oxide 3 bismuth-borosilicate glass frit 22(around 600° C. melting point)

[0060] The enamel composition thus prepared was deposited on a clearglass sheet (PLANILUX®; thickness: 2.1 mm) by screen printing in a wetmedium (coating thickness: 22 μm). The sheet coated with the compositionwas heated to 220° C. (time: 3 minutes). After cooling, a uniformscratch-resistant coating having an L* value of 15 was obtained.

[0061] The aforementioned glass sheet (large pane) was placed on ahorizontal bending frame, the face coated with the enamel compositionturned upward, and a second sheet 2.1 mm in thickness, of slightlysmaller size (small pane), made of glass of the same type as the firstbut devoid of any enamel composition. The assembly was heated to about580-600° C. (duration: 8-10 minutes) and then cooled to roomtemperature. The large pane was coated with a black enamel about 16 μmin thickness, having the following calorimetric coordinates (measuredunder the conditions of Example 1): L*=5−6; a*≦0.5 and b*≦0.5.

COMPARATIVE EXAMPLE

[0062] This example was produced under the conditions of Example 1, butmodified in that, on the one hand, the enamel composition was differentand, on the other hand, the thickness of the layer deposited by screenprinting was 24 μm.

[0063] The composition contained (in percentages by weight): Part A:sodium silicate 25 water 15 sodium hydroxide in an amount sufficient toobtain a pH of 10.5; Part B: copper oxide 25 bismuth-borosilicate glassfrit 5 (around 680° C. melting point) soda-lime float glass frit 30(around 730° C. Littleton point)

[0064] After bending, the large pane was coated with a gray enamel,having a yellowish tendency, with the following calorimetric coordinates(measured under the conditions of Example 1): L*=15; a*=0.8 and b*=1.7.

[0065] In the examples according to the invention, the enameled glasssheets obtained after the bending step were easily separated (nosticking point). Moreover, it was found that the enamel heated via thelarge pane face (the 2 face of the glazing in the final position) wasuniformly distributed over the surface of the glass and also that thesmall pane face (the 3 face) in contact with the large pane contained notrace of enamel.

1. A water-based black enamel composition capable of being deposited ona glass substrate, comprising: 20 to 40% by weight of water-solublesodium silicate and/or potassium silicate; a water-soluble base, in anamount sufficient for the pH of the composition to be at least 10.5; 5to 25% by weight of water; 40 to 60% by weight of a metal oxide chosenfrom the group consisting of copper oxides, iron oxides, cobalt oxides,mixtures of these oxides and mixtures of at least one of said oxideswith chromium oxide(s); less than 10% by weight of zinc oxide; at least10% by weight of a glass frit having a melting point below 680° C.; andless than 10% by weight of a glass frit having a Littleton point above700° C.
 2. The composition as claimed in claim 1, characterized in thatthe metal oxide is chosen from mixtures of chromium oxide(s) and copperand/or iron oxide(s).
 3. The composition as claimed in claim 2,characterized in that the metal oxide is copper chromite, iron chromiteor a mixture of these chromites.
 4. The composition as claimed in one ofclaims 1 to 3, characterized in that the metal oxide consists entirelyof copper chromite.
 5. The composition as claimed in one of claims 1 to4, characterized in that it comprises 50 to 60% by weight of metaloxide.
 6. The composition as claimed in one of claims 1 to 5,characterized in that it comprises 10 to 30% by weight of glass frithaving a melting point below 680° C.
 7. The composition as claimed inone of claims 1 to 6, characterized in that it comprises 20 to 30% byweight of water-soluble sodium silicate and/or potassium silicate. 8.The composition as claimed in one of claims 1 to 7, characterized inthat it comprises from 10 to 20% by weight of water.
 9. The compositionas claimed in one of claims 1 to 8, characterized in that it comprises 1to 6% by weight of zinc oxide.
 10. The composition as claimed in one ofclaims 1 to 9, characterized in that it comprises 4 to 10% by weight ofglass frit having a Littleton point above 700° C.
 11. The composition asclaimed in one of claims 1 to 10, characterized in that the meltingpoint of the glass frit is below 600° C.
 12. The composition as claimedin claim 11, characterized in that the melting point is between 500 and600° C.
 13. The composition as claimed in one of claims 1 to 12,characterized in that the frit having a melting point below 680° C. is abismuth-borosilicate, zinc-borosilicate or lead-borosilicate glass fritor a mixture of said frits.
 14. The composition as claimed in one ofclaims 1 to 13, characterized in that it includes ingredients forlowering the expansion coefficient, of the zirconium silicate oraluminum silicate type.
 15. The composition as claimed in claim 14,characterized in that the ingredients for lowering the expansioncoefficient are added in proportions from 5 to 25% and preferably from10 to 20%.
 16. A glass sheet, at least one of its faces of which is atleast partially coated with the enamel composition as claimed in one ofclaims 1 to
 15. 17. The glass sheet as claimed in claim 16,characterized in that it is coated with the composition according toeither of claims 14 and 15, said composition being deposited right tothe edge.
 18. Laminated glazing, especially for automobiles, consistingof at least two glass sheets separated by at least one sheet of organicmaterial, said glazing comprising at least one glass sheet coated atleast partially on at least one of its faces with the enamel compositionas claimed in one of claims 1 to 15.